Silica filler pretreated with bio-based polyol and elastomer composition containing the same

ABSTRACT

In one embodiment, a filler composition includes a filler including silica; and a bio-based oil contacting the filler and including at least one soy polyol, wherein an elastomer, if present, is less than 25 weight percent of the total weight of the filler composition. The filler composition does not contain appreciable amount of petroleum oil, which if present, is less than 25 weight percent of the filler composition. The filler composition does not contain appreciable amount of epoxidized oil which, if present, is less than 25 weight percent of the total weight of the filler composition. The soy polyol may include a hydroxyl number of from 10 to 350 KOH/g. The bio-based oil may further include soy oil.

TECHNICAL FIELD

The present invention relates to silica filler pretreated with bio-basedpolyol and elastomer composition containing the same.

BACKGROUND

Typical elastomer formulations for automotive applications such asgaskets, floor mats, splash shields and radiator shields usepetroleum-derived materials. For example, EPDM (ethylene propylene dienemonomer), formulations often incorporate portions of petroleum oil,synthetic elastomer and carbon black. Additional applications mayinclude shoes, conveyor belts and tires.

Conventional elastomer formulations using petroleum oil have been metwith limited use. Being derived from petroleum, petroleum oil is anon-renewable resource. Many uncertainties associated with the use ofpetroleum-derived materials reside in the long-term economic instabilityand limited reserves of fossil fuels and oils. The production of thepetroleum-derived materials requires a great deal of energy, as the rawpetroleum oils are drilled, extracted from the ground, transported torefineries, refined, and processed to yield the petroleum oils. Theseefforts add to the cost of petroleum oils and hence the cost of thefinal elastomer products.

There is a continuing need for “greener” elastomer products made fromraw materials that are more versatile, renewable, less costly and moreenvironmental friendly.

SUMMARY

In one embodiment, a filler composition includes a filler includingsilica; and a bio-based oil contacting the filler and including at leastone soy polyol, wherein an elastomer, if present, is less than 25 weightpercent of the total weight of the filler composition. The fillercomposition does not contain appreciable amount of petroleum oil, whichif present, is less than 25 weight percent of the filler composition.The filler composition does not contain appreciable amount of epoxidizedoil which, if present, is less than 25 weight percent of the totalweight of the filler composition. The soy polyol may include a hydroxylnumber of from 10 to 350 KOH/g. The bio-based oil may further includesoy oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a non-limiting sample process of premixing filler withbio-based oil according to one or more embodiments;

FIGS. 1B1 and 1B2 depicts a way of rolling mixing the premix in relationto FIG. 1A; and

FIG. 2 depicts elongation values of a list of prepared compositionsaccording to the example(s) described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to compositions, embodiments, andmethods of the present invention known to the inventors. However, itshould be understood that disclosed embodiments are merely exemplary ofthe present invention which may be embodied in various and alternativeforms. Therefore, specific details disclosed herein are not to beinterpreted as limiting, rather merely as representative bases forteaching one skilled in the art to variously employ the presentinvention.

Except where expressly indicated, all numerical quantities in thisdescription indicating amounts of material or conditions of reactionand/or use are to be understood as modified by the word “about” indescribing the broadest scope of the present invention.

The description of a group or class of materials as suitable for a givenpurpose in connection with one or more embodiments of the presentinvention implies that mixtures of any two or more of the members of thegroup or class are suitable. Description of constituents in chemicalterms refers to the constituents at the time of addition to anycombination specified in the description, and does not necessarilypreclude chemical interactions among constituents of the mixture oncemixed. The first definition of an acronym or other abbreviation appliesto all subsequent uses herein of the same abbreviation and appliesmutatis mutandis to normal grammatical variations of the initiallydefined abbreviation. Unless expressly stated to the contrary,measurement of a property is determined by the same technique aspreviously or later referenced for the same property.

Silica such as precipitated silica and/or fumed silica may be used as areinforcement agent in tire tread compounds to reduce rolling resistanceand is integral to increasing fuel economy. Silica is hydrophilic orpolar. Because the polar silica is not readily compatible with thenonpolar elastomer matrix, there have been constant searches for mixingmethods to ensure adequate incorporation of the silica filler in theelastomer matrix.

It has been surprisingly found, according to one or more embodiments ofthe present invention, that a silica-containing filler can bepre-treated with a bio-based oil such as soy polyol to form a pretreatedfiller, which can then be combined with elastomer to form a elastomercomposition provided with industrially acceptable or better properties,including relatively improved elongation values, while being moreeconomically efficient and more environmentally friendly. Variouselastomer products can be formulated by using a bio-based oil treatedfiller composition. There are several distinctive benefits associatedwith the elastomer products thus formulated. For instance, the additionof pretreated filler, such as soy polyol treated silica, improves theprocessability of the resulting elastomer composition. In certaininstances, the resulting elastomer composition has relatively improvedelongation. In certain other instances, adding the pretreatedsilica-containing filler to the Banbury mixer results in relativelylower dusting. These benefits are additional to the benefits inproviding significant cost savings and alleviating environmentalconcerns.

The bio-based oil may be alternatively referred to as sustainable oil,which is in direct contrast to non-sustainable oil such as petroleumoil. The bio-based oil may include one or more vegetable and seed oilsand their polyols. Non-limiting examples of the vegetable and seed oilsinclude soy oil, rapeseed oil, canola oil, peanut oil, cotton seed oil,sunflower oil, olive oil, grape seed oil, linseed oil, castor oil; fishoil and oils derived from other animal fats. In certain instances, thebio-based oil may include one or more of vulcanized soy oil, epoxidizedsoy oil, degummed soy oil, tall oil, linseed oil, castor oil, and orangeoil.

The bio-based oils can be derived from a variety of sources such as pinetrees, soybeans and oranges. Degummed soy oils can be obtained fromsoybeans. Tall oil can be obtained from pine trees. Linseed oils can beobtained from flax seeds. Castor oils can be obtained from castorplants. Orange oils can be obtained from orange peels. Vulcanizedsoybean oils can be obtained from soybeans. The soy oil is then degummedin order to remove the lecithin or gummy substance within the oil.

Most plant oils are aliphatic triglycerides and have variouscombinations of alkane (single carbon bonds), alkene (double carbonbonds) and alkyne (triple carbon bonds) groups depending upon the chosenplant source. Oils extracted from soybeans, flax seeds and castor seedsare rich in triglycerides. The fatty acids are unbranched aliphaticchains of four to twenty eight carbons in length which are attached to acarboxyl group. The unsaturation within the fatty acids providesopportunities for bonding within the elastomer matrix. The unsaturationof the triglycerides may contribute to the compound's hardness due tocross linking between the fatty acid chains.

The bio-based oil may include one or more oils having a saturation levelof less than 30 percent, 25 percent, 20 percent, 15 percent or 10percent. Such oils may include soybean oil which has a saturation levelof 13 to 17 percent, castor oil which has a saturation level of 1 to 5percent, linseed oil which has a saturation level of 7 to 11 percent,low saturation soy oil which has a saturation level of 5 to 9 percent,or flaxseed oil which has a saturation level of 6 to 10 percent.

In certain instances, the bio-based oil includes soy polyol andoptionally soy oil. Soy oil may alternatively be referred to asnon-hydroxyl-functionalized soy oil and soy polyol may alternatively bereferred to as hydroxyl-functionalized soy oil.Non-hydroxyl-functionalized soy oil can be extracted from soybeanplants, and/or soy polyol (hydroxyl-functionalized soy oil) is a productof hydroxyl-functionalization of a soy oil. The term“hydroxyl-functionalized” refers to a reaction or a process whereby oneor more hydroxyl groups (—OH) are added to the soy oil molecule. Theterm “functionality” refers to an average number of isocyanate reactivesites per molecule of soy polyol. It can be calculated according to thefollowing formula: average functionality=(total moles polyol)/(totalmoles OH). The term “hydroxyl number” refers to a measure of the amountof reactive hydroxyl groups available for reaction. By way of example,this value can be determined by a wet analytical method and is reportedas the number of milligrams of potassium hydroxide equivalent to thehydroxyl groups found in one gram equivalent of a sample.

Soy polyol involves relatively less harmful emissions during elastomerformulations than the petroleum oil used alone. There is an estimate ofabout 5.5 kilograms of carbon dioxide reduction per kilogram polyolproduced from soybeans relative to petroleum sources, as soybeanssequester carbon dioxide during growth. Moreover, because soy polyolsare produced from plants, they are a renewable raw material and are thusmore environmentally friendly.

As a natural source for the soy oil and soy polyol, the soybean or soyabean is characterized as a bushy, green legume related to clover, peasand alfalfa. The pods, stems and leaves are covered with fine brown orgray hairs. Together, oil and protein account for about 60% of drysoybeans by weight; protein at 40% and oil at 20%. The remainderconsists of 35% carbohydrate and about 5% ash. The principal solublecarbohydrates, saccharides, of mature soybeans are the disaccharidesucrose (range 2.5-8.2%), the trisaccharide raffinose (0.1-1.0%)composed of one sucrose molecule connected to one molecule of galactose,and the tetrasaccharide stachyose (1.4 to 4.1%) composed of one sucroseconnected to two molecules of galactose. Because soybeans contain nostarch, they are a good source of protein for diabetics.

The non-hydroxyl-functionalized soy oil can be isolated or extractedfrom the soybeans using any suitable methods, including the solventextraction method. In particular, the soybeans are cracked, adjusted formoisture content, rolled into flakes and solvent-extracted withcommercial hexane. The oil is then refined, blended for differentapplications. In general, the major unsaturated fatty acids in soybeanoil triglycerides are 7% linolenic acid (C-18:3); 51% linoleic acid(C-18:2); and 23% oleic acid (C-18:1). It also contains the saturatedfatty acids 4% stearic acid and 10% palmitic acid.

The soy oil as directly isolated and extracted from the soybeans, likemost other vegetable oils, contain no hydroxyl groups in theirtriacylglycerol structures of saturated and unsaturated fatty acids. Forexample, crude soy oil consists of about 17 percent saturatedtriglycerides and about 83 percent unsaturated triglycerides, with about4.41 double bonds per triglyceride molecule.

The soy polyol or the hydroxyl-functionalized soy oil can be derivedfrom the extracted soy oil using any suitable methods. For instance, toconvert the extracted soy oil into soy polyol, hydroxyl groups can beadded onto the fatty acid backbone of the extracted soy oil via methodsincluding blowing air through a soy oil, heating the soy oil to anelevated temperature over room temperature and/or adding a catalyst topromote hydroxylation reaction in the soy oil.

It is noted that hydroxyl functionalization is carried out on soy oilsthat have been extracted out. Any oil molecules incidentally retainedwithin the soy meal, soy flour, soy hull, soy protein, or other soyremnants after oil extraction cannot be effectively hydroxylated.Therefore, incidental inclusion of soy oil from soy meal, soy flour, orsoy protein is not expected to effect any appreciable hydroxylationuseful for carrying out one or more embodiments of the presentinvention.

The extracted soy oil and or the hydroxyl-functionalized soy polyolcontain primarily triglycerides of fatty acids, which are composed of acarboxyl group attached to a longer chain of hydrocarbons; can besaturated, that is they do not contain any carbon-carbon double bonds,or unsaturated such that they contain carbon-carbon double bonds. Thenon-hydroxyl-functionalized soy oil as extracted and thehydroxyl-functionalized soy polyol may each have a differentdistribution and concentration of carbon-carbon double bonds andhydroxyl groups; and as a result, each may give the final elastomerproduct different characteristics with respect to reaction speed andcompletion, viscosity, and composition. Without being limited to anyparticular theories, there and other differences remain to be whatdistinguish the isolated soy oil component from the conventionalpetroleum oil as used as the sole oil component in the conventionalelastomer products.

The hydroxyl-functionalized soy polyol, as used according to one or moreembodiments of the present invention, can be obtained commercially, forinstance, under the brand name SoyOyl® R2-052 available from UrethaneSoy System Company (USSC). SoyOyl® R2-052 is a two-functional polyolmade from unmodified soy oil.

The soy polyol is optionally further processed to reduce volatilecontents from the soy polyol. For instance, a vacuum stripping techniquecan be utilized, such as a wiped film evaporator method, to separatevolatiles from the polyol. The soy polyol can be introduced into aheated cylindrical vacuum chamber and through thin-film wiping orsweeping actions, the volatiles vaporize and condense on the inner wallof the vacuum chamber. The condensed liquid, which contains mostlyvolatile compounds, can be removed.

The soy polyol is optionally further processed to include antioxidantsto prevent further oxidation across unreacted double bonds in thepolyol. Adding antioxidants helps to reduce formation of aldehydes.Non-limiting examples of antioxidants that can be used in accordancewith the present invention include PUR68 and PUR55, available from CibaSpecialty Chemicals of Charlotte, N.C.

The soy polyol can have any suitable molecular weight, as defined asconventional number-average molecular weight. The molecular weight of agiven soy polyol can be measured using a Waters gel permeationchromatograph equipped with Waters 2487 dual λ absorbance detector, aWaters 2414 refractive index detector, and two Waters Styragel® HR 1 THFcolumns. The flow rate of the tetrahydrofuran eluent can be set at 1mL/min, at 40° C. Polystyrene standards with narrow molecular weightdistributions can be used for molecular weight calibration and,therefore, the molecular weight results are relative molecular weights.Exemplary polystyrene standards have molecular weight of 0.93×10³,1.05×10³, 1.26×10³, 1.31×10³, 1.99×10³, 2.97×10³, 3.37×10³, 4.49×10³,4.92×10³, and 5.03×10³ Daltons.

According to one or more embodiments of the present invention, the soypolyol has functionality in a range of 1.0 to 5.0, and in particularinstances, has functionality of 1.0, 1.3, 1.5, 1.8, 2.8, 3.0, 3.5, or4.0.

The bio-based oil does not include appreciable amount of petroleum oil.When incidentally included, petroleum oil is of no greater than 25percent, 15 percent, 5 percent, 1 percent, 0.1 percent, or 0.005 percentby weight of the total weight of the filler composition or the finalelastomer composition including the filler composition.

The term “petroleum oil” may refer to naturally occurring mixture ofhydrocarbons of various weights, as a result of conventional oilextraction processes known in the art. The hydrocarbon may includealkanes, cycloalkanes, and various aromatic hydrocarbons. The petroleumoil as used herein may include organic compounds such as nitrogen,oxygen, and sulfur, and trace amounts of metals such as iron, nickel,copper, and vanadium. By way of example, the petroleum oil may include83 to 87 weight percent of carbon, 10 to 14 weight percent of hydrogen,0.1 to 2 weight percent of nitrogen, 0.5 to 6 weight percent of sulfur,and any combinations thereof.

The petroleum oil may include at least one of paraffinic oil, naphthenicoil, aromatic oil, polyethylene polyol, polypropylene polyol, acrylicpolymer polyol, polyolefin polyol and polystyrene polyol. Compared tosoy polyol which includes one or more triglyceride backbone, thesepetroleum derived polyols may not.

In one or more embodiments, the bio-based oil does not includeappreciable amount of epoxidized oil. When incidentally included,epoxidized oil is of no greater than 25 percent, 15 percent, 5 percent,1 percent, 0.1 percent, or 0.005 percent by weight of the total weightof the filler composition or the final elastomer composition includingthe filler composition. The epoxidized oil may be an epoxidized soy oil.

According to another aspect of the present invention, a method offorming an elastomer composition includes a premixing step of mixingsilica with soy polyol together prior to mixing with an elastomer. Asdepicted in FIG. 1A and FIGS. 1B1 and 1B2, this premixing step may beperformed for a period of time, for instance, a period of 10 hours, 17hours, 24 hours, 31 hours or 38 hours. This premixing step may becarried out at or near ambient temperature, for instance, 23 to 27degrees Celsius, at or near ambient pressure, for instance, 0.8 to 1.2bar, and/or at a mixing speed of from 30 to 60 rpm The premix may thenbe mixed with elastomer and other components in an upside-down method inwhich the soy polyol and silica pre-mix composition is added to theBanbury before addition of the elastomer.

In the filler composition, a weight ratio of silica to soy polyol may beof from 1.5 to 2.5, 1.7 to 2.3 or 1.9 to 2.1.

The method may then include mixing the resultant premix of silica andsoy polyol with elastomer and other components in a multi-pass mixingmethod, which can be a method including two passes, three passes or morepasses as need. An non-limiting example of the multi-pass mixing methodincludes first, second and third mixing. In the first mixing, the mixingcontainer is set at a temperature of between 60 to 70 degrees Celsiusand is set with a filler factor of between 65 to 75 percent. The premixof soy polyol and silica is placed inside the mixing container,optionally with one or more other components such as carbon black; thenelastomer is placed on top. The mix is mixed for up to 1 minute, 2minutes, 3 minutes, 4 minutes or 5 minutes and then released at anelevated temperature of 140 to 180 degrees Celsius. The upside-downmethod means placing elastomer on top in the Banbury mixer, which isdifferent than the pre-mixed roller process of rolling the silica in theoil. The roller does not rotate up and down. There are either 2intermeshing or 2 tangential mixtures that rotate towards each other andpull the mix between the blades and the walls of the chamber to build upshear forces. At the end of the first pass, the mix is released out ofthe roller chamber and then is returned back to the same chamber for thesecond pass.

In the second pass, the mix from the first pass is placed back in theroller (for instance, a Banbury mixer or roller) and then one or moreprocessing aids such as zinc oxide, stearic acid and/or wax are placedin with a gap in time of no less than 5 second, 10 second, 15 seconds,or 20 seconds, and no greater than 2 minutes, 1 minute, 45 second, or 35seconds. This sequence of addition of chemicals/materials has beenparticularly useful to get a good mixing of elastomer, filler and oil,without premature cure of the elastomer compound. In this connection,surfur is added in the final of the passes (the 3^(rd) of 3 passes orthe 2^(nd) or 2 passes, for instance) since shorter mixing times andlower temperatures are sometimes preferable to reduce premature curingof the rubber or elastomer. Therefore the mixing temperature should becarefully handled to avoid unnecessary cure in the Banbury mixer. Duringthe first pass, we focus on getting good dispersion of the filler andoil into the elastomer. In this connection, silica, fillers and soypolyol are added in the first pass to ensure good mixing and to completethe chemical reaction involving the silane coupling agent.

In the third pass, the starting temperature and the ending temperatureare generally lower than those in the first and second pass. Thestarting temperature for the third pass may be 5, 10, 15, 20 or 25degrees lower and the ending temperature for the third pass may be 15,30, 45, or 60 degrees lower than those of the first and second pass. Theelastomer containing mix from the second pass may be added in batchesinto the roller such as the Banbury during this third pass. Forinstance, the second pass mix may be added in half, followed by theaddition of sulfur and accelerators, and then the other half of thesecond pass mix. The accelerator and sulfur are added only during thelast third step to reduce premature cure, where temperature isrelatively lower and mixing time is relatively shorter.

According to one or more embodiments of the present invention, thesilica-containing filler may further include carbon black or a fillerblend of carbon black and an ancillary filler selected from the groupconsisting of soy protein, soy meal, soy flour, soy hull, andcombinations thereof.

The soy protein as used herein can be a rigid material, containingcertain functional groups, such as carboxylic acids and substitutedamine groups which may make coupling with coupling agents. Various formsof dry soy protein can be used, including those available under thebrands of PRO-FAM®, ARDEX®F, ARCON®, TVP®, and SOYLEC®. The soy proteinmay be ground to any suitable size. In particular instances, the dry soyprotein can be ground to sizes in a range of 10 to 150 microns, 20 to140 microns, 30 to 130 microns, or 40 to 120 microns. For comparisonpurposes, conventional carbon black is of sizes in a range of 10 to 60nanometers.

The dry soy protein is optionally chemically modified to increasetoughness and water resistance. For instance, Wu et al., (Studies on thetoughness and water resistance of zein-based polymers by modification,Polymer, 44, 3901-3908 (2003)) modified protein by using low molecularweight polycaprolactone (PCL)/hexamethylene diisocyanate (HDI)prepolymer. Through a chemical reaction between the amino acid in theprotein, and HDI modified PCT, a urea-urethane linkage in the proteinand PCL prepolymer complex can be formed, leading to an increase intoughness and water resistance of the modified soy protein.

The soybean meal may refer to the material remaining after solventextraction of oil from soybean flakes. Soybean meal may be toasted withmoist steam and ground in a hammer mill.

The soy flour may refer to defatted soybeans where special care is takenduring desolventizing (not toasted) in order to minimize denaturation ofthe protein to retain a high Nitrogen Solubility Index (NSI), for usessuch as extruder texturizing (TVP). It is the starting material forproduction of soy concentrate and soy protein isolate. Defatted soyflour is obtained from solvent extracted flakes, and contains less than1% oil.

The ancillary filler may include one or more of the following materials:calcium carbonate, sericite, alumina, magnesium carbonate, titaniumoxide, clay, talc, magnesium oxide, and aluminum hydroxide.

In one or more embodiments, the elastomer may include one or more ofnatural elastomer, solution styrene butadiene elastomer (SBR), emulsionSBR, butadiene elastomer (BR), butyl elastomer (IIR), styrene isoprenebutadiene elastomer (SIBR), polybutadiene, isoprene-butadiene elastomer(IBR), acrylonitrile butadiene elastomer (NBR), chloroprene elastomer,ethylene propylene diene monomer (EPDM), and combinations thereof. Incertain particular instances, the elastomer is ethylene-propyleneethylidene norbornene.

The elastomer composition may be formed into articles of various shapesand for different uses. These articles include tire treads, gaskets,floor mats, splash shields, shoes, conveyor belts and radiator shields.

The elastomer article as described herein can be used for both interiorand exterior vehicle applications, wherein the elastomer article mayhave one or more of the following characteristics: a percent elongationof greater than 150%, 250%, 350%, 450%, or 550%; a tensile strength ofgreater than 5 MPa, 5.5 MPa, 6 MPa, or 6.5 MPa; a tear resistance ofgreater than 25 KN/m, 30 KN/m, 35 KN/m, 40 KN/m, or 45 KN/m; and ahardness value of greater than 60 Shore A, 65 Shore A, 70 Shore A, or 75Shore A. In accessing these various properties of the elastomerarticles, the following methods can be illustratively employed: ASTMD412 for measuring tensile strength and percent elongation, ASTM D624for measuring tear resistance, and ASTM D2240 for measuring hardness.

In particular, tensile strength and percent elongation (% elongation)can be measured in accordance with ASTM D412. Specimens with one inchgrip width and 5.5 inches in total length are stamped from 12.5millimeter thick slabs using a tensile bar die. An Instron Model 5565with 500N load cell in a tensile geometry is used to pull the samples ata cross-head velocity of 50 mm/min. Tensile strength and % elongationvalues are recorded for approximately five samples per set.

Suitable elastomers include natural elastomer (NR), polybutadieneelastomer (BR) and styrene butadiene elastomer (SBR), or combinations(blends) thereof.

Elastomeric compounds may be characterized using suitable analysismetrics, including Dynamic Mechanical Analysis (DMA). In addition, curetime and curing temperature may be used to assess kinetic properties andphysical properties may be analyzed based on tensile, elongation, tearand durometer.

Having generally described several embodiments of this invention, afurther understanding can be obtained by reference to certain specificexamples which are provided herein for purposes of illustration only andare not intended to be limiting unless otherwise specified.

EXAMPLE Example 1

A non-limiting method of mixing silica-containing filler in elastomercompounds may include a multiple-pass mixing method. Multiple passmixing method may be desirable to accommodate the temperature-sensitivereaction often associated with the use a coupling agent such as a silanecoupling agent and/or to facilitate adequate shear to disperse thesilica.

To evaluate the ease of processing the elastomer within a manufacturingenvironment, several tests can be performed on the elastomer compounds,including Mooney Viscosity and Mooney Scorch. Higher viscosity levelsmake processing and extruding the elastomer more difficult.

Aromatic oil can be used as the baseline for the model formulations dueto its prevalence in tread compounds in the past. Naphthenic oil can beincluded as another comparison of potential oils to replace aromaticoils. Petroleum oils are commonly used in elastomer compounding asprocessing aids and plasticizers to lower viscosity, improvelow-temperature flexibility and yield a softer product.

Tread formulations are compounded in a Farrel Model F270 Banbury Mixerusing a 70% fill factor with ram pressure set to 50 psi. The elastomeris mixed using a multi-pass system, with the elastomers, pre-treatedfillers, processing oil and silane coupling agent added in the firstpass. The cure activators, antidegradants and processing aid are addedto the master batch in the second pass. In the first two mixing stages,the rotor speed is increased after the ingredients are incorporated inorder to bring the batch temperature to 160° C. to complete thesilanization reaction. The primary and secondary accelerators and sulfurare mixed with the master batch in the final (productive) pass.

Precipitated silica is used as a reinforcement agent in tire treadcompounds to reduce rolling resistance and is integral to increasingfuel economy. Silica is hydrophilic and pretreating with soybean oilcoats the silica and can lead to better dispersion and improvedproperties. The effect of using soy oil, soy polyol, epoxidized soy oil,and low saturation soy oil to pretreat the silica is examined, withresidual aromatic extract (RAE) petroleum oil used as a control. The useof soy oil as a pretreatment can increase the compatibility of theelastomer matrix and precipitated silica filler. Without wanting to belimited to any particular theory, it is believed that the silica and thebio-based oil is merely physically combined/mixed at this pre-mixingstep without inducing any chemical reactions. In certain instances, thesilica going into the premixing roller may have been pretreated with acoupling agent such as a silane coupling agent.

Soy-based oils offer a range of chemical properties compatible withdifferent types of elastomers used in tire tread applications.Pretreating silica with soy polyol provides the resultant elastomercomposition with improved processability, elongation and tearresistance. If soy-oils are able to be used as full replacement ofpetroleum processing oils, a twenty pound passenger tire could use up toone pound of this sustainable product. The environmental benefit becomeseven more significant if the technology is able to be migrated acrossall passenger tires in the U.S. If successful, up to 28 million poundsof soy oil could be utilized in this capacity per year.

Silica-filled elastomer samples are mixed in a multi-pass methodaccording to the schedule depicted in Table 1.

TABLE 1 exemplified multi-pass mixing schedule First Mix - upside-downmixing Start Temperature 65° C. Start Rotor Speed 65 rpm Fill Factor 70%Pressure 50 psi Mixing Sequence At 0 minute, add carbon black, silica,oil, Si69, and then add elastomer on top At 1 minute, sweep Hold for 3to 6 minutes after sweep Dump at 160° C. Second Mix Start Temperature65° C. Start Rotor Speed 65 rpm Fill Factor 70% Pressure 50 psi MixingSequence At 0 minute, add first pass mix at 0 minute At 30 seconds, addzinc oxide, stearic acid, processing aid and wax At 1 minute, sweep Mixfor 2 to 5 minutes after sweep Dump at 160° C. Third Pass StartTemperature 50° C. Start Rotor Speed 60 rpm Fill Factor 70% Pressure 50psi Mixing Sequence At 0 minute, add half of the second pass mix At 15seconds, add sulfur and accelerators At 30 seconds, add remaining secondpass mix At 1 minute, sweep Mix for 90 seconds after sweep Dump at 110°C.

Example 2

Compounding and testing are evaluated for the premix compositions listedin Table 2 shown below, which are then compounded with elastomeraccording to the procedure illustrated in Table 1 above:

a) Soy oil and silica preblended 24 hours

b) Soy oil and silica not preblended

c) Aromatic oil and silica preblended 24 hours

d) Aromatic oil and silica not preblended

e) Soy polyol (50 OH#) and silica preblended 24 hours

f) Epoxidized soybean oil and silica preblended 24 hours

g) Low saturation soy oil and silica preblended 24 hours

TABLE 2 Main Weight Percentages Ingredients Function a b c d e f g SBR(50% Elastomer   36% vinyl and 25% styrene) Buna CB Elastomer   12% 1203Carbon Filler  4.8% black Zeosil Silica 28.9% 1165 MP Si69 Coupling 2.3% Agent Holly Aromatic   0 0 16% 16% 0 0 0 Sundex Oil 8000EU CargillSoy Oil   16% 16% 0 0 0 0 0 Soy Oil Low Soy Oil   0 0 0 0 0 0 16%Saturation Soy Oil Galata Ex-   0 0 0 0 0 16% 0 ESBO poxidized Soy OilSoy Soy   0 0 0 0 16% 0 0 Polyol 50 Polyol KOH/g

Premixing of the oil and silica filler in the roller occurs before thisstep of the Banbury mixing process. This chart includes all of thematerials added in the Banbury.

While compounding the elastomer for this study, it is noted that thereis a significant advantage in processing for the preblended soy polyol,low saturated soy oil and epoxidized soy oil formulations, forinstances, as indicated in samples “e”, “f” ang “g” stated herein. Theelastomer easily dumps from the Banbury without sticking to the wallsand the doors. It is also much easier to sheet out on the two-roll mill.This can be a distinct advantage in a production environment. Theprocessability of the control and preblended compounds are displayed ona 5-point point scale in Table 3.

TABLE 3 Processability of preblended and control silica formulationsFormulations Processability* a) Soy oil and silica, preblended 24 hours1 b) Soy oil and silica, not preblended (control) 1 c) Aromatic oil andsilica, preblended 24 hours 1 d) Aromatic oil and silica, not preblended(control) 1 e) Soy polyol (50 OH#) and silica, preblended 24 hours 5 f)Epoxidized soybean oil and silica, preblended 24 5 hours g) Lowsaturation soy oil and silica, preblended 24 hours 3 *Processability isassessed on a scale of 1 to 5, with 1 representing relatively worseprocessability and 5 representing relatively better processability.

Elongation is measured in these preblended compositions. FIG. 2illustratively demonstrates that the soy oil, soy polyol and low-sat soyoil preblended compounds exhibit relatively higher elongation.

While the best mode for carrying out the invention has been described indetail, those familiar with the art to which this invention relates willrecognize various alternative designs and embodiments for practicing theinvention as defined by the following claims.

What is claimed:
 1. An elastomeric composition comprising: a fillerincluding silica; a bio-based material including a soy polyol; and anelastomer present in an amount less than 25 weight percent of theelastomeric composition, the weight ratio of silica to the soy polyolbeing 1.5 to 2.5.
 2. The elastomeric composition of claim 1, furthercomprising a petroleum-based oil present in an amount of less than 25weight percent of the elastomeric composition.
 3. The elastomericcomposition of claim 1, wherein the bio-based material further includesa soy oil.
 4. The elastomeric composition of claim 1, further comprisingan epoxidized oil present in an amount of less than 25 weight percent ofthe elastomeric composition.
 5. The elastomeric composition of claim 1,wherein the filler and the bio-based oil are intermixed.
 6. Theelastomeric composition of claim 1, wherein the soy polyol has ahydroxyl number of from 10 to 350 KOH/g.
 7. The elastomeric compositionof claim 1, wherein the filler further includes carbon black.
 8. Theelastomeric composition of claim 1, wherein the filler further includesan ancillary filler.
 9. The elastomeric composition of claim 8, whereinthe ancillary filler is selected from the group consisting of soyprotein, soy flour, soy meal, soy hull and combinations thereof.
 10. Theelastomeric composition of claim 1, wherein the weight ratio of silicato soy polyol is in the range of 1.7 to 2.3.
 11. The elastomericcomposition of claim 1, wherein the weight ratio of silica to soy polyolis in the range of 1.9 to 2.1.
 12. A cured elastomeric compositioncomprising: a filler including silica; a bio-based material including asoy polyol; and an elastomer present in an amount less than 25 weightpercent of the elastomeric composition, the weight ratio of silica tothe soy polyol being 1.5 to 2.5.
 13. The cured elastomeric compositionof claim 12, wherein the weight ratio of silica to soy polyol is in therange of 1.7 to 2.3.
 14. The elastomeric composition of claim 12,wherein the weight ratio of silica to soy polyol is in the range of 1.9to 2.1.
 15. An elastomeric composition comprising: a precipitated silicamaterial; a soy polyol; and an elastomer present in an amount less than25 weight percent of the elastomeric composition, the weight ratio ofthe precipitated silica material to the soy polyol being 1.5 to 2.5. 16.The elastomeric composition of claim 15, further comprising a couplingagent.
 17. The elastomeric composition of claim 15, further comprisingan aromatic oil.
 18. The elastomeric composition of claim 15, whereinthe weight ratio of silica to soy polyol is in the range of 1.9 to 2.1.